Conventionally, a process, such as etching processing performed on an object to be treated, e.g., a semiconductor wafer, is carried out by a plasma etching apparatus under a low temperature, high rate and dry condition.
FIG. 5 is a cross sectional view showing internal structure of a plasma etching apparatus.
As shown in FIG. 5, a plasma treatment container 1 of the plasma etching apparatus includes a processing chamber 2 therein and an upper electrode 3 made of conductive material is disposed at a top portion thereof. In the processing chamber 2, a lower electrode 4 made of a conductive material is disposed to face the upper electrode 3, and a semiconductor wafer 6, the object to be treated, is adsorbed to be held on an upper surface of the lower electrode 4 through an electrostatic chuck 5. Along a circumference of the container 1, a permanent magnet 7 is disposed in such a manner that its magnetic field is parallel with the semiconductor wafer 6, the object to be treated.
The upper electrode 3 is provided with a plurality of gas discharge openings 8 through which a processing gas including fluoride such as CF4 and NF3, chloride of BCl3, SnCl4 and the like, and bromide such as HBr is supplied to the processing chamber 2.
Further, the lower electrode 4 is supported by an elevating column 9 which can be lifted and lowered by a driving device along a direction indicated by an arrow A, and is connected to a high frequency power supply through a matching unit. Bottom and side surfaces of the lower electrode 4 are protected by an electrode protection member 10 while bottom and side surfaces of the electrode protection member 10 are covered with a conductive member 11. Disposed between the conductive member 11 and a bottom of the container 1 is an expandable and contractible bellows 12 made of a conductive material such as stainless steel.
Disposed beneath the bottom surface of the electrode protecting member 10 is a tubular member 13 made of a conductive material into which the elevating column 9 is inserted to penetrate therethrough. And fixedly attached on the side surface of the electrode protection member 10 is an exhaust ring 14 of a flange shape. Further, an insulation ring 15 is disposed between an end surface of the electrode protecting member 10 and a side surface of the electrostatic chuck 5. Disposed below a lower surface of the exhaust ring 14 is a bellows cover 16 which is extended downwards therefrom. And vertically disposed on the bottom surface of the container 1 is a bellows cover 17 in such a manner that it overlaps with a portion of the bellows cover 16.
In the container 1 arranged as described above, after a position of the semiconductor wafer 6 is adjusted by moving the elevating column 9 along the direction of the arrow A, a high frequency power is supplied from the high frequency power supply to the lower electrode 4 through the elevating column 9 functioning as a power supply rod. Then, the processing gas introduced into the processing chamber 2 depressurized to a predetermined vacuum ambience is transformed into plasma, so that a desired process is performed on the masked semiconductor wafer 6 by a plasma etching.
In the course of plasma etching process, plasma treatment container internal members, such as the electrode protection member 10, the tubular member 13, the exhaust ring 14, the insulation ring 15 and the bellows covers 16 and 17, are severely damaged by the processing gas transformed into the plasma, i.e., by the so-called plasma erosion. Thus, plasma-resistant material is used therefor.
Among these plasma treatment container internal members, the ones whose base material is Al, Al alloy, aluminum oxide and the like are rendered plasma-resistant by forming an oxide film (alumite film) on a surface of the base material. Further, in a case where abundant halogen and oxygen gases are used in order to increase effectiveness of the plasma etching processing, lifetime of the alumite film on a surface of the plasma treatment container is shortened. Thus, there has been suggested a method for manufacturing a more plasma-resistant plasma treatment container internal member by forming a thermally sprayed film made of Y2O3 on a surface of the base material (see, for example, Japanese Patent Application No. 1999-351546.
As shown in FIGS. 6A to 6D, this method includes the steps of preparing a base material 601 with a surface treated by machining (FIG. 6A); forming an alumite film 602 on a surface of the base material 601 by an anodic oxidation treatment (FIG. 6B); next, performing a blast treatment of spraying Al2O3, SiC, sand and the like on the alumite film 602 (FIG. 6C); and then, forming a thermally sprayed film 603 by a plasma thermal spray treatment (FIG. 6D).
In the aforementioned method, the blast treatment is performed because roughening the surface by spraying Al2O3, SiC, sand and the like increases adhesivity of the thermally sprayed film 603 formed of Y2O3 serving as a plasma-resistant material to the alumite film 602.
Since, however, a blasting direction of Al2O3, SiC, sand and the like is straight, the blasting treatment only can be performed on a simple surface, and a quantitative treatment cannot be performed on shaded regions, such as sidewalls of a slit and a hole.
Further, in case of the base material 601 (FIG. 6B) treated by anodic oxidation, significant increase in adhesion of the thermally spayed film 603 cannot be achieved.
Therefore, in the course of CO2 blasting carried out by blowing a dry ice to clean the plasma treatment container internal member, the thermally sprayed film 603 is often peeled off.
An object of the present invention is to provide a plasma treatment container internal member capable of improving adhesivity of a thermally sprayed film to a surface of a base material thereof and a plasma treatment apparatus having the plasma treatment container internal member.